Kenwood TS-440S Serivce Manual page 6

TS-440S
CIRCUIT DESCRIPTIO N
I=1800, J=7244, K=19800, L=3239, M=4 1
fin = 0 .388 fsTD 1 1
When fIN = 30 MHz (USB mode) in formula 10 , f IN an d
fSTD have the following relationship :
I = 1800, J = 7244, K = 19800, L = 3239, M = 7 3
.' . fIN = 0 .833 f STD
1 2
Since the precision of the reference crystal oscillator use d
in the TS-440 is 10 ppm (—10 to 50°C) and the receive r
system has the characteristics shown in items i) and ii), th e
total accuracy is stable at any point from 30 kHz to 30 MHz .
The maximum amount of frequency shift is only +/— 30 0
Hz (see formula 12 ) . The characteristic shown in ite m
iii) enables variable band functions such as IF shift to be im -
plemented, using the microprocessor . The microprocesso r
also is used to set carrier points by adjusting fcAR, and to se t
and adjust the amount of IF shift .
So far received frequencies in the SSB mode have been dis -
cussed . For receive modes other than SSB, and in transmi t
mode, operating frequency is determined by the referenc e
frequency and frequency division data .
In CW receive mode, fvco is shifted down 800 Hz and used
as fvco3 . In AM or FM receive mode, fCAR generation i s
stopped . In FM receive mode, fHET is modulated by addin g
audio signals to VCO5 from the microphone . FSK (RTTY) i s
transmitted in LSB mode and uses AFSK by adding audio sig -
nals externally .
The type of frequency displayed differs, depending on th e
mode, as shown in Table 1 .
Mode Displayed frequenc y
USB, LSB, FS K
C W
AM, FM
Carrier point frequenc y
Transmission carrier frequenc y
IF filter center frequency
Table 1 Displayed frequencie s
3 . Receiver Circuit Description
IC
2
C335 7
f
I F AMP .
DE T
Noise S O
CF
3
CFW455
Fig . 3 Receiver circuit configuratio n
CF I
Q7, 8
3SK73GRx2
IC
7
µPC2002V
S P
SSB
C .F
AF P A
CF
2
C . F
6